thermal analysis of single cylinder … int. j. mech. eng. & rob. res. 2014 ashish p jadhao and...

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Int. J. Mech. Eng. & Rob. Res. 2014 Ashish P Jadhao and Ajitabh Pateriya, 2014

THERMAL ANALYSIS OF SINGLE CYLINDERDIESEL ENGINE PISTON

Ashish P Jadhao1* and Ajitabh Pateriya1

*Corresponding Author: Ashish P Jadhao,[email protected]

This paper describes the stress distribution of the single cylinder diesel engine piston by usingFEA. ProE wildfire 4.0 Computer Aided Design (CAD) software was used to design the existingpiston. The main objectives is to investigate and analyze the temperature distribution and heatflux of piston at the real engine condition during combustion process. The paper describes theuse of finite element analysis technique to predict the higher stress and critical region on thecomponent. The original diesel engine piston is coated by using different materials for specificthickness. The optimization is carried out to reduce the stress concentration on the upper endof the piston, i.e. (piston head/crown and piston skirt and sleeve). The coating analysis is testedusing ANSYS workbench 11.0 thermal analysis.

Keywords: Diesel engine piston, Piston skirt, ProE, ANSYS workbench, Temperatureconcentration, Thermal analysis

INTRODUCTIONA piston is a cylindrical piece of metal thatmoves up and down inside the cylinder whichexerts a force on a fluid inside the cylinder.Pistons have rings which serve to keep the oilout of the combustion chamber and the fueland air out of the oil. Most pistons fitted in acylinder have piston rings. Usually there aretwo spring compression rings that act as a sealbetween the piston and the cylinder wall, andone or more oil control ring s below thecompression rings. The head of the piston can

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Int. J. Mech. Eng. & Rob. Res. 2014

1 PDAM., Dr. V.B Kolte College of Engineering, Malkapur, M.S., India.

be flat, bulged or otherwise shaped. Pistonscan be forged or cast. The shape of the pistonis normally rounded but can be different. Figurebelow shows the part of piston engine. Aspecial type of cast piston is the hypereutecticpiston. The piston is an important componentof a piston engine and of hydraulic pneumaticsystems (Smart, 2006). Piston heads form onewall of an expansion chamber inside thecylinder. The opposite wall, called the cylinderhead, contains inlet and exhaust valves forgases.

Research Paper

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As the piston moves inside the cylinder, ittransforms the energy from the expansion of aburning gas usually a mixture of petrol or dieseland air into mechanical power in the form of areciprocating linear motion. From there thepower is conveyed through a connecting rodto a crankshaft, which transforms it into a rotarymotion, which usually drives a gearbox througha clutch (Auto Zentro, 1990).

TYPES OF PISTONOn this new modern century, many type ofpiston that have been design or already in themarket. Every type of piston has their capabilityand also has limitation. Some of these typeswill now be considered (Stratman, 2010).

Two-Stroke PistonFigure shows two stroke piston that be madeby casting process. These pistons are mainlyused in gasoline and diesel engines forpassenger cars under heavy load conditions.They have cast-in steel strips but are notslotted. As a result, they form a uniform bodywith extreme strength.

Cast Solid Skirt PistonCast solid skirt pistons have a long servicelife. Furthermore this piston more useable thatcan be used in gasoline and diesel engines.Besides that, their range of applicationsextends from model engines to large powerunits as shown in Figure below. Piston top, ringbelt and skirt form a robust unit.

Figure 1: The Part of the Piston Consisting of Many Parts that be Assemble

Source: NASIOC (2008)

Figure 2: Two Stroke Piston

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Forged Solid Skirt PistonFor this piston as shown in Figure below, thereare made by forged process that gives thepiston more strength. This type of piston canmainly be found in high performance seriesproduction and racing engines. Besides that,due to the manufacturing process, they arestronger and therefore allow reduced wallcross-sections and lower piston weight. Also,due to relative manufacturing procedures,forged pistons tend to be more expensive thanother process.

LITERATURE REVIEWKong et al. (1995) classified diesel combustionmodel into two groups; thermodynamic andmultidimensional. In our study we focus onthermodynamic-type model. Thethermodynamic type models emphasize thethermodynamics aspects of an engine systemwith the major concern of energy conservation.The typical application of these types of modelsin diesel engine Numerical Modeling is tocalculate the heat release rate according to agiven pressure history. These models intend todescribe the real engine processes byconsidering temporal and spatial variations ofthe temperature, pressure and turbulence withinthe combustion chamber. Lu Xiaoming et al.(2005) carried out combustion analysis thatmainly includes heat release analysis, cylinderpressure and fuel injection pressure traceinterpretation. Heat release analysis, includingrate of heat release and its integral curve wasbased on cylinder pressure data recorded.Bicheng Gui et al. (2004) define about thecombustion model and characteristic of light-duty DI diesel engine fueled with dimethyl ether(DME). In this paper they gives the detailedchemical kinetics of DME which is chemicalkinetic of DME which is useful to studycombustion model of DME as fuel.

Ganesan (2000) defines and gives ideaabout different models that occur incombustion modeling, i.e., heat release andheat transfer model, adiabatic f lametemperature model which is essential tocalculate it in combustion modeling further hehad given different equations for NumericalModeling for C.I. Engine processes.

Su et al. (1996), University of Wisconsin-Madison characterization of high pressure

Figure 3: Piston Cast Solid Skirt Piston

Figure 4: Forged Solid Skirt Piston

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diesel sprays has been performed bothexperimentally and numerically. Theexperimental study was conducted using a fuelinjection system which has a capability ofproducing multiple injection sprays. TheNumerical study can be conduct using theKIVS-II code for the operating conditions usedin the spray experiments. The KIVAcalculations show reasonable agreement withthe experimental results, and indicate that thepresent spray breakup model characterizesthe physical phenomena well at pressures andinjection velocities currently seen in dieselengines.

Haworth (2005) focused on the device-scale Computational Fluid Dynamics (CFD)-based in-cylinder turbulent combustionmodeling for reciprocating-piston Internal-Combustion (IC) engines. In this paper hedefine that the combustion process in ICengines is characterized by complexturbulence-chemistry interaction that spanmultiple combustion regimes: premised flamepropagation, mixing-controlled burning, andchemical-kinetics-controlled processes mayoccur simultaneously within a single device.

Rutland et al. (1995) apply a individualmodel for each part of combustion process,i.e., 1) Spray model, 2) turbulence model,3) ignition model, 4) combustion model. Anignition model is used whenever and whereverthe temperature is lower than 10000 K and ifthe temperature is higher than 10000 K thencombustion model is activated describing hightemp chemistry. Ayoub and Rolf Reitz (1995)define the ignition modeling in which theignition characteristics of a diesel fuel areassumed to be given by the local CetaneNumber (CN) of that fuel at each point in the

combustion chamber. The higher the CN, themore readily the fuel ignites, and vice versathey gives the eight reactions involved inkinetic model from which they conclude thatfor higher values of CN, the activation energydecreases resulting in shorter ignition delaysand vice versa.

Colin Ferguson and Allan Kirkpatrick (2000)defines that the combustion process can beclassified into three phases which are ignitiondelay, premixed combustion and mixingcontrolled combustion and explain about allphases and changes occur in it. Senator et al.(2000) define that a detailed experimentaldescription of combustion evolution in dieselengines is extremely complex because of thesimultaneous formation and oxidation of air/fuel mixture. Therefore they simplified the heatrelease rate equation by considering variousassumptions

Suryavanshi et al. (2005). Themathematical models described in the variousliteratures developed by number ofinvestigators provide a flexible tool for theanalysis of transient hydraulic and mechanicalphenomena that occur in an operating fuelinjection system. Mathematical simulation isvery powerful tool for studying fuel injectionsystem response to changes in design andoperating parameters. The results ofcalculations obtained from the computerprogram shows that the results obtained arequite similar to those obtained by otherinvestigators and also they are according toexpectation. Gowd et al. (1995). The four-stroke DI diesel engine with hemi-sphericalbowl in piston was considered for analysis. Theglobal parameters, such as, pressure, turbulentkinetic energy and emissions were predicted

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using KIVA CFD code with two turbulencemodels, namely, standard k – Є and RNG k –Є turbulence models. The parameters werecompared with the experimental values. Thepredicted in-cylinder peak pressures were 6.7MPa and 6.3 MPa with the standard k – Є andRNG k – Є turbulence models, respectively..The experimental peak pressure was only 6.1MPa Between the two turbulence models usedin the computations,the RN k – Є turbulencemodel predictions were very close to themeasured values.

PRESSURE CALCULATIONSSo the piston crown/head, piston ring and thepiston skirt should have enough stiffness whichcan endure the pressure and the frictionbetween contacting surfaces. In addition, asan important part in engine, the workingcondition of piston is directly related to thereliability and durability of engine. So it isimportant for the piston skirt and the piston ringto carry out structural and optimal analysiswhich can provide reference for design ofpiston. The formula can be expressed as,

310602/

NALPmIHP ...(1)

where,

Pm – Mean effective pressure (bar);

L – Stroke length (mm);

A – Area (mm2);

N – Speed (rpm);

IHP – Indicated Horse Power (watt)

Remember that the system is in equilibriumso the gas is supporting not only the piston butthe atmosphere as well. The gas is isolatedfrom the atmosphere.

P = F/A

F = 23 kg * 9.81 = 226 N

Area = pi r^2

r = d/2 = 28/2 = 14 cm = 0.14 m

Area = 3.141592 * 0.14^2 = 0.0616 m^2

P = 226/0.0616

= 3670 N/m^2 = 3670 pascals

1 atmosphere = 101325 pascals

Therefore the pressure inside the cylindermust be 101325 pascals + 3670 pascals =104995 Pascals.

Youngs Modulus (GPa) 90 90 200 30 175

Poissons Ratio 0.3 0.27 0.22 0.25 0.2

Density (Kg/m3) 2700 7870 6080 2800 5740

Thermal Expansion (x 10-6 1/°C) 21 12 10.7 5.3 9.1

Thermal Conductivity (W/mK) 155 16.1 2.12 3.3 1.56

Specific Heat (J/kgK) 960 764 640 950 490

Weight Of Piston (Kg) 2.931 5.0659 4.9245 4.665 4.897

Weight of coat for 0.15 mm thickness (Kg) 0 2.1349 1.9935 1.734 1.966

Table 1: Data Used for Analysis

ExistingMaterial AlSi

Coat ofNiCrAl

Coat of3YSZ

Coat ofMullite

Coat ofLa2Zr2O6

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Now we can use PV = nRT to solve for n.(the number of moles of the gas).

P = 104995 Pa

V = Area * h

V = 0.0616 m^2 * 0.77 m (how did I get that?See the radius calculation above).

V = 0.0474 m^3

MULLITE MATERIAL PROPERTYMullite or porcelainite is a rare silicatemineral of post-clay genesis. It can form twostoichiometric forms 3Al2O32SiO2 or 2Al2O3

SiO2. Unusually, mullite has no chargebalancing cations present. As a result, thereare three different Al sites: two distortedtetrahedral Al sites and one Al other sitewhich adopts a higher co-ordinateoctahedral state.

Mullite is a good, low cost refractoryceramic with a nominal composition of3Al2O3 • 2SiO2. The raw materials for mulliteare easily obtainable and are reasonablypriced. It has excellent high temperatureproperties with improved thermal shock andthermal stress resistance owing to the lowthermal expansion, good strength andinterlocking grain structure.

REFERENCES1. Abu-Nada E, Al-Hinti I, Al-Sarkhi A and

Akash B (2008), “PresentedThermodynamic Analysis of PistonFriction in Spark-Ignition InternalCombustion Cngines”, pp. 133-145,Department of Mechanical Engineering,Hashemite University, Zarqa 13115,Jordan, Institution of MechanicalEngineers, London.

2. Ashwinkumar S Dhoble and Sharma R P(1993), “Focused of Engine IndustryResearch and Development was onReducing the Engine Out Emissions CO,HC, NOx and Particulate Matter (PM) R&D Centre”, Mahindra & Mahindra Ltd.,Nashik, SAE Project 930797.

3. Ayoub N S and Rolf D Reitz (1995),“Multidimensional Modeling of FuelComposition Effects on Combustion andCold Starting of Diesel Engines”, SAE No.952425.

4. Balasubramanyam M S et al. (2004),“CFD Modeling of the in-Cylinder Flow inDirect Injection Diesel Engine”, Elsevier,Computers and Fluids, pp. 995-1021.

5. Bicheng Gui, Tat Leung Chan, Chun WahLeung, Jin Xiao, Hewu Wang and

Maximum 651.46 °C 651.19 °C 650.2 °C 650.07 °C 650.37 °C Mullite isTemperature better inAttend thermal

distribution

Equivalent Stress 2.2827e+007 Pa 7.9121e+006 Pa 1.1267e+007 Pa 4.0451e+006 Pa 1.0824e+007 Pa Mullite is better

Shear Stress 7.9094e+006 Pa 2.4048e+006 Pa 3.5692e+006 Pa 1.0263e+006 Pa 3.4139e+006 Pa Mullite is better

Max Principal Stress 1.5217e+007 Pa 4.7623e+006 Pa 6.7375e+006 Pa 2.1777e+006 Pa 6.3244e+006 Pa Mullite is better

Table 2: Results

ExistingMaterial AlSi

No CoatCoat of NiCrAl Coat of 3YSZ Coat of

MulliteCoat of

La2Zr2O6 Remark

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Longbao Zhao (2004), “Modeling Studyon the Combustion and EmissionsCharacteristcs of a Light-Duty DI DieselEngine Fueled with Dimethyl Ether (DME)Using a Detailed Chemical KinetcsMechanism”, SAE No. 2004-01-1839.

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14. Nabani et al. (1993), “Kinetics andApplication CFD Modeling Codes”, Vol.4, pp. 1-12, Pergamon Press Ltd.

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16. Sanjay Shrivastva, Kamal Shrivastava,Rahul S Sharma and Hans Raj K (2004),“Presented Finite Element Modeling anAnalysis of Automotive Piston”, Journalof Scientific & Industrial Research,Vol. 63, December, pp. 997-1005.

17. Sazhin S and Sazhing E (2007), “SystemDecomposition Technique for SprayModeling in CFD Codes”, Elsevier,Computers and Fluids, pp. 601-610.

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20. Suryavanshi, Akash, Rameshbabu et al.(2005), “Devolopment and Application ofa Comprechensive Soot Model for 3DCFD Reacting Flow Studies in a DieselEngine”, Elsevier, Combustion andFlame, pp. 11-26.

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Transfer”, Proceedings of the WorldCongress on Engineering, Vol. III, July 6-8, WCE, London, UK.

22. Tulus, Ariffin A K, Abdullah S andMuhamad N (2006), “Presented the HeatTransfer Model of Piston Pin”,Proceedings of the 2nd IMT-GT RegionalConference of Mathematics, June 13-15,Statistics and Applications, UniversitySains Malaysia.

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